Belmont Barber Chair

Hi I have a 3 1949 Belmont Barber Chairs that me and father been using for years !! The chair looks like the last Koken Barber Chair made before Belmont bought out Koken the kind with the greenish/yellowish porcelin stem base. The problem that I am having with my chair is when I just picked up my third chair to complete the set I noticed that my chair wouldn't pump an down . I took off the the seat cushion and when I took off the hydrolic fluid cover I noticed that the plunger rod snapped. I found a new one and installed it and now the hydrolics work fine the last thing that I have to fix is that the brake does not lock when I pull back on the arm of the chair . I pulled the whole assembly out of the chair and I tried three seperate brakes that I had every one the I put into the slot doesn't work and when I put the assembly back into the stem of the chair I did it jently so the brake wouldn't fall out of it's spot and the brake still doesn't lock the chair !! When I pull the assembly back out of the chair the brake is still in the right spot meaning it didn;t fall in the chair but still doesn't work. I noticed when I put the brake piece in the slot I notice alittle play in there and I don't know if the brake is suppose to fit tight in there and that is why the brake isn't working. If anyone can help me I appreciate it I can still use the chair but I'm scarred using the chair in my shop if i don't hol it and if a customer walks up and I'm not holding the chair it will kick out an someone will fall and get hurt Thanks, Bob